COMPOUNDS WITH POLYATOMIC IONS
polyatomic ion – a covalently bonded group of atoms, possessing a net charge
oxyanions – polyatomic ions that contain oxygen and have a negative charge
anion – negative ion
cation – positive ion
POLYATOMIC IONS
e.g.,
Name
Formula
sulfate
SO42–
carbonate
CO32–
nitrate
NO3–
chlorate
ClO3–
phosphate
PO43–
hydroxide
OH–
ammonium
NH4+
Na3PO4
sodium phosphate
magnesium chlorate
Mg2+
ClO31─
Mg(ClO3)2
ammonium sulfate
NH41+
SO42─
(NH4)2SO4
-
from the common oxyanions, we derive others
ClO4
ClO3
perchlorate
chlorate
1 more oxygen
common polyatomic ion (memorized)
ClO2
ClO
-
chlorite
hypochlorite
1 less oxygen
2 less oxygens
if H is added to the polyatomic ion, add +1 to the valence of the polyatomic ion
the prefix bi or the word hydrogen is used in the polyatomic ion’s name
e.g.,
carbonite ion
CO22─
bicarbonite ion or hydrogen carbonite ion
HCO2
copper(II) bicarbonite
Cu2+
HCO21─
Cu(HCO2)2
sodium hydrogen phosphate
Na1+
HPO42─
Na2HPO4
copper(II) nitrate
Cu2+
NO3
Cu(NO3)2
ammonium sulfite
NH41+
SO32─
(NH4)2SO3
CaCO
calcium hypocarbonite
HOMEWORK:
p. 96-97 #15, 16 (not i), 17 (not e, g, h, i, j, l, n, o, r, s, t, u, x, y), 18
(not c).
HYDRATES
-
compounds that contain water as part of their ionic crystal structure
Hydrates can be purified by heating to drive the water out of them. This produces an
anhydrous compound.
e.g.,
copper(II) sulfate pentahydrate
Cu2+ SO42─
CuSO45H2O
calcium chloride dihydrate
Ca2+ Cl1
CaCl22H2O
Hydrate names use Greek prefixes to indicate the number of water molecules.
Greek prefixes
Meaning
mono
di
tri
tetra
penta
hexa
hepta
octa
nona
deca
1
2
3
4
5
6
7
8
9
10
HOMEWORK:
pages 97 #19, 20(not c), 21.
NAMING MOLECULAR COMPOUNDS
-
e.g.,
use Greek prefixes to indicate the number of atoms of that element
**(mono is never used on the first name)
N2O
dinitrogen monoxide
CF4
carbon tetrafluoride
The name tells how many of each element are in the formula.
e.g.,
dinitrogen tetroxide
N2O4
dihydrogen monoxide
H2O
- when double vowels, sometimes one vowel is dropped
HOMEWORK:
page 98 #22, 23.
ACIDS
- formulas start with hydrogen
There are two types of acids: binary acids and oxyacids (contain polyatomic ions)
Binary Acids
- contain two different elements (H and another element)
- named hydro________ic acid
e.g.,
HCl
hydrogen monochloride
HCl(aq)
hydrochloric acid
HF
hydrogen monofluoride
HF(aq)
hydrofluoric acid
Oxyacids
- acids that contain a polyatomic ion that consists of oxygen
naming:
- if polyatomic ion ends ate, name of acid is polyatomic name with ate changed to
ic acid
- if polyatomic ion ends ite, name of acid is polyatomic name with ite changed to
ous acid
e.g.,
H2SO4
hydrogen sulphate
H2SO4(aq)
sulfateic acid
sulfic acid (sulfuric acid)
HNO2
hydrogen nitrite
HNO2(aq)
nitrous acid
HNO3
hydrogen nitrate
HNO3(aq)
nitric acid
Formulas:
phosphoric acid
H1+
PO43
H3PO4(aq)
hydrobromic acid
H1+
Br1─
HBr(aq)
hypochlorous acid
H1+
ClO1─
HClO(aq)
BASES
e.g.,
strong bases contain hydroxide ions
NaOH(aq)
sodium hydroxide
Ba(OH)2(aq)
barium hydroxide
aluminum hydroxide
Al3+
OH1─
Al(OH)3(aq)
cesium hydroxide
Cs1+
OH1─
CsOH(aq)
HOMEWORK:
page 101 #24 (not e, f), 25 (not c, g and only the IUPAC name).
page 101 #26 (mistake in b: Ca(OH)2), 27.
page 103-104 #16 (not f, p), 17, 18 (not e), 19 (not d, e, f, g, h, q,
s, x), 20.